Intangible Assets (Estimated Amortization Expense Over Next Five Years) (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Finite-Lived Intangible Assets [Line Items]
2022, Other intangible assets	$ 281
2023, Other intangible assets	265
2024, Other intangible assets	242
2025, Other intangible assets	225
2026, Other intangible assets	209
Total, Other intangible assets	1,222
Other Intangible Assets [Member]
Finite-Lived Intangible Assets [Line Items]
2022, Other intangible assets	99
2023, Other intangible assets	94
2024, Other intangible assets	88
2025, Other intangible assets	87
2026, Other intangible assets	85
Total, Other intangible assets	453
The Chubb Corporation [Member]
Finite-Lived Intangible Assets [Line Items]
2022, Other intangible assets	182
2023, Other intangible assets	171
2024, Other intangible assets	154
2025, Other intangible assets	138
2026, Other intangible assets	124
Total, Other intangible assets	769
The Chubb Corporation [Member] | Agency distribution relationships and renewal rights [Member]
Finite-Lived Intangible Assets [Line Items]
2022, Other intangible assets	196
2023, Other intangible assets	177
2024, Other intangible assets	160
2025, Other intangible assets	144
2026, Other intangible assets	130
Total, Other intangible assets	807
The Chubb Corporation [Member] | Fair Value Adjustment to Acquired Loss Reserves [Member]
Finite-Lived Intangible Assets [Line Items]
2022, Other intangible assets	(14)
2023, Other intangible assets	(6)
2024, Other intangible assets	(6)
2025, Other intangible assets	(6)
2026, Other intangible assets	(6)
Total, Other intangible assets	(38)
Balance of FV adjustment on Unpaid Losses and Loss Expenses	$ 90	$ 110